The NSW Department of Environment and Climate Change has been ordered to pay costs expected to be well above $30,000 for adjourning a hearing into a long-running prosecution for alleged illegal land clearing.

A two week hearing was scheduled to start in the NSW Land and Environment Court on Monday into the alleged illegal clearing of 423 hectares of farm land at Walgett by David Gleeson.

The Department started action against Mr Gleeson in December 2003 following a complaint of illegal clearing made by a former employee of Mr Gleeson's, Stephen McLeish, according to Mr Gleeson's Sydney-based solicitor, Paul McGirr.

Mr Gleeson is pleading not guilty.

But, despite twice advising that it was ready to proceed with a hearing and evidence had closed, the department this week suddenly applied for an adjournment because it needed more time to gather information for its case.

While Justice Jagot, who was to hear the case, allowed the case to be adjourned, he ordered the Department to pay legal costs because the two week hearing had been ready to proceed.

Mr McGirr expects the department will be forced to pay more than $30,000 for adjourning the long-running case.

There has been no comment yet from the NSW Department of Environment and Climate Change.